1. Field of the Invention
The present invention relates to a vehicle state estimation device configured to estimate at least state quantities of at least a sprung of a vehicle.
2. Description of the Related Art
In a vehicle such as an automobile, state quantities of a sprung or unsprungs of a vehicle are sometimes estimated as parameters for executing vehicle control such as a vehicle running motion control and the like. For example, as described in Japanese Patent Application Laid-open Publication No. H6-48139, there is disclosed a suspension control device that is configured to estimate speeds of unsprungs relative to a sprung based on wheel speeds of wheels and driving operation input by a driver and to control damping forces of shock absorbers of the wheels.
In the suspension control device disclosed in the above Laid-open Publication, speeds of unsprungs relative to a sprung are estimated based on wheel speed of each wheel and driving operation input by a driver utilizing a vehicle model. In general, however, as characteristics of a vehicle changes in accordance with conditions such as driving operation input by a driver and the like, if actual characteristics shift from those of a vehicle model, accuracy in estimating speeds of unsprungs relative to a sprung lowers. It is not easy to correct a vehicle model successively in accordance with actual vehicle characteristics that change with driving operation input by a driver and the like.